Drill grinder



A. M. LOHR DRILL GRINDER July 1, 1952 2 SHEETS--SHEET 2 Filed Dec. 28, 1948 Patented July 1, 1952 UNITED STATES PATENT OFFICE DRILL GRINDER Albert M. Lohr, East Lampeter Township, Lancaster County, Pa., assignor to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania Application December 28, 1948, Serial No. 67,670

2 Below the disc 66 is a second disc ll which is also keyed to shaft M. The two discs l6 and I1 constitute the work holding assembly designated generally at [8.

the drills all be of substantially the same length. 5 In order to accommodate drills of differing In gang drilling machines such as those used lengths, the top disc i6 is adjustable toward and in the manufacture of perforated acoustical tile, away from the lower disc H, The mechanism it is desirable that the drills be of substantially by which this is accomplished is shown in Figuniform effective length so that the perforaure 4. This cross-sectional view shows the tubutions which are drilled through a substantial 10 lar shaft I4 disposed within the housing i5. extent of the thickness of the tile are of uniform Positioned within the tubular shaft I4 is an eledepth. The term effective length used herein vating rod 19 which is free for limited movement refers to the length of the drill between the tip up and down with respect to shaft 14. It is shown and the shoulder which is provided at the botin its uppermost position in Figure 4. The top tom of the enlarged upper portion or shank of of the rod I8 is provided with a threaded portion the drill. In drilling acoustical tile on a large- 20 which is in engagement with a threaded memscale mass-production basis, it is necessary that her 2|, received within a keeper 22 which is sethe drills be resharpened periodically to produce cured to gear I 3 by means of studs 24 and 25. clear-cut perforations. In resharpening the drills Secured to the threaded member 2| by means skill must be exercised so that all the drills are 20 of a set screw 25 is a hand wheel 21. Rotation of uniform length. Prior to this invention, this of the hand wheel 21 raises and lowers the rod was a hand operation and required a great deal IS with respect to the tubular shaft [4. of time. The top adjustable disc l6 of the work holder An object of this invention is to provide a I8 is attached to the elevating rod 19 and is grinding device in which a series of drills may 25 driven by the hollow shaft l4 through a pin 28 be rapidly and accurately sharpened in such a which is received within an elongated vertical manner that all the drills are of substantially the slot 29 in the shaft 14 and is fixed to the rod 19. same effective length. The elongated vertical slot 29 allows the pin 28 In order that my invention may be more readto move in a vertical direction with respect to the ily understood, itwill be described in connection 30 shaft Hi. It will be clear from this disclosure with the attached drawing in which: that raising and lowering of the elevating rod Figure 1 is an elevational view of the drill l9 will raise and lower the top disc [6 of the grinder of my invention partially broken away; work holder 18, with respect to the lower holder Figure 2 is a cross-sectional View taken on the H, and the work holder assembly l8 will be roline II-II of Figure l; tated as a unit with shaft 14, through the gear Figure '3 is an enlarged view of the work holder; reduction unit Iii-l 3 powered by motor 5. Figure 4 is a cross-sectional view showing the Positioned below the work holder assembly l8 mechanism for rotating the work holder; and is a second motor 30 (Figure l) which is mounted Figure 5 is a cross-sectional view taken on the on the upright support 3. Attached directly to line VV of Figure 3. 4.0 the motor 30 is a grinding wheel 3| provided with Referring to Figure 1, there is shown a base 2 a bevel 32 which is positioned immediately below and an upright support 3 on the top of which is work holder assembly l8 and slightly off center mounted a gear housing 4. On top of the gear with respect thereto. The position of the grindhousing 4 is mounted a motor 5 provided with ing wheel is such that the drills positioned in 1 a gear-reduction drive 6 which is coupled to a openings 34 in the two discs I6 and I! will conshaft 7 by means of a coupling 8. Shaft l is a tact a portion only of the bevel of the grinding 1 vertical shaft disposed within a housing 9. wheel during a relatively short portion of their Keyed to shaft 1 immediately below the coupling 360 path of travel. This is illustrated in Figure 8 is a gear I!) which drives a reduction gear train 5 in which the position of the grinding whee1 is i made up of gears 'l I, I2, and I3 disposed in the shown in dotted lines. The center of the grindgear housing 4. ing Wheel is designated by the numeral 33. The

Gear i3 is keyed to a vertical tubular shaft point of contact between the drills and the grind- Hi (Figure 4) which is housed within housing l5. ing wheel is designated by the numeral .35. The Keyed to shaft I l below the housing I5 is a disc motor 30 upon which the grinding wheel 3| is 16 which is adapted to rotate with the shaft I4, 6

mounted may be adjusted horizontally by means of hand wheel 36 which operates a screw 31 which is in threaded engagement with a threaded housing 38 secured to the upright support 3. Rotation of the hand Wheel 36 moves the motor mount in a horizontal direction in guides 39. The motor 39 and the grinding wheel 3| are also adjustable in a vertical direction by hand wheel d which is attached to a screw ll which is in threaded engagement with a lug 42 attached to the vertical slide it and capable of movement in guideway 8 3. By these adjustments, the grinding wheel may be raise-d or lowered, retracted or extracted, by turning the hand Wheels 36 and 40 to bring the operating surface of the wheel into proper position. It is possible to use grinding wheels of different diameter and thickness, if desired, by making appropriate adjustments.

In order that the individual drills d be rotated while in contact with the grinding wheel, a rubber belt G6 is provided which is driven by pulley i! secured to the end of shaft l which, as explained before, is coupled directly to the reducedspeed drive 6 of motor 5. The belt 4i travels around the pulley El and idler pulleys 48 and 49 which rotate on columns 50 and 5!, respectively, depending from the bottom of the gear housing These have been omitted from Fig-- ure 1, but are shown in Figure 3. The path of travel of the belt 46 is such that it rotates the drills during that portion of the 360 path of travel of the drills with the work holder in which the drills are engaged by the grinding wheel and are being ground. While in the preferred embodiment a rubber belt is used to rotate the drills,

it will be understood that other means such as gears and gear racks may be used. The drills are placed in openings 34 provided in discs 16 and H, the discs being so arranged that the holes are in vertical alignment. The individual drills are provided with an enlarged upper portion embodying chuck engaging means. This enlarged upper portion is larger than the holes in the work holder assembly and, therefore, the shoulder s on the under side of the drill shank prevents the drill from falling through the openings 34 of the work holder. This shoulder also acts as the locating point which determines the length of the drill. In order to prevent the drills from being pushed upwardly by the grinding wheel 3| when they come in contact therewith, there is' provided a hold-down mechanism shown generally at 52. This hold-down mechanism is comprised'of aseries of spring-urged shoes 53 which the drill shanks engage during their path of travel in engagement with the grinding wheel. These spring-urged hold-down shoes 53 prevent the drills from being jarred upwardly and keep them in engagement with the grinding wheel during their path of travel through the short are in which they contact the same.

I have found that for best results the speedreduction drive 6- should rotate the shaft l at approximately 16 R. P. M. and the gear train comprised of gears l0, ll, l2, and I3 should be of such a ratio as to drive the discs l6 and I! at a speed of 1 R. P. M. Since shaft 1 rotates at 16 /2 R. P. M., the pulley M rotates at the same speed and, therefore, the belt 45 travels at approximately the'rate of 12 feet per minute. This rotates the drills at suhicient speed so that they make several revolutions during the short space of travel in which they contact the grinding wheel.

The ,disc I? is; provided with aseries of pins 54 (Figures 4 and 5) which are positioned between holes 34 and slightly to the rear thereof to engage the belt 46 in the event all of the holes 34 are not filled with drills. The disc ii is also provided with four guide pins 55 which are rigidly attached thereto by means of studs 56 and pass through holes in disc It. These guide pins keep the two discs in proper alignment so that the drills will be inserted in a true vertical position. The guide pins 55 pass freely through the disc 15 to enable disc i@ to be raised and lowered and still held in proper vertical alignment.

The device of my invention is not limited for use in grinding twist drills, but may be used for grinding tubular drills as well.

In the operation of my device, the drills to be ground are placed in the holes 3% provided in the work holding assembly l3. As shown in the drawing, the discs I6 and Il are provided with twenty holes for accommodating drills. The drills are placed in the holes and the machine is started. As the work holder rotates, after the drills are no longer in. engagement with the belt 65, they may be manually removed from the holder and inspected. If additional grinding is necessary, the drill is reinserted so that it travels past the grinding wheel a second time. If the drill is satisfactorily ground, another drill is inserted in the holder and the operation continued until the entire series of drills is ground uniformly.

While I have illustrated and described certain preferred embodiments of my invention, it will be understood that the same is not so limited, but may be otherwise practiced within the scope of the following claims.

I claim:

1. In a drill grinding device the combination of a support for rotatably receiving a plurality of drills aligned in a circumferential path with their axes parallel, said support comprising two disc-like members, one movable with respect to the other to accommodate drills of different lengths, a rotatable abrading element for dressing the tips of said drills, means for rotating said support to bring said drills sequentially into abrading relationship with said rotatable abrading element, and means for rotating said drills in said support while in abrading relationship with said rotatable abrading element.

2. In a drill grinding device the combination of a support for rotatably receiving a plurality of drills aligned in a circumferential path with their axes parallel, said support comprising two disc-like members, one movable with respect to the other to accommodate drills of different lengths, guide pins secured to one of the disclike membersand passing through the other disclike element to keep them in alignment, a rotatable abrading element for dressing the tips of said drills, means for rotating said support to bring said drills sequentially into abrading relationship with said rotatable abrading element, and means for rotating said drills in said support while in abrading relationship with said rotatable abrading element.

3. In a drill grinding device the combination of a support for rotatably receiving a plurality of drills aligned in a circumferential path with their axes parallel, a driving belt for engaging said drills, said support being provided with pins to engage said belt, a rotatable abrading element for dressing the tips of said drills, means for rotating said support to bring said drills sequentially into abrading relationship with said rotatable abrading element, and means for rotating said drills in said support while in support while in abrading relationship with said 15 rotatable abrading element.

ALBERT M. LOHR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 816,550 Holub Mar. 27, 1906 993,981 Grover May 30, 1911 1,255,693 Bell V Feb. 5, 1918 1,531,281 Garbin Mar. 31, 1925 2,397,459 Armbrust Apr. 2, 1946 FOREIGN PATENTS Number Country Date 338,058 Great Britain NOV. 13, 1930 

